1. Field
The invention relates to techniques for obtaining a near-field equivalent source (NFES) representation of wireless devices for determining specific absorption rate (SAR).
2. Background
Modern wireless devices such as cellular phones are generally required to meet radio frequency (RF) exposure requirements as mandated by domestic and international standards and regulations. To ensure compliance, such devices must currently undergo an extensive certification process prior to being shipped to market. The certification process may entail performing a large number (e.g., thousands) of measurements on each device to determine the RF exposure of the device under different operating scenarios.
For example, to assess a parameter known as specific absorption rate (SAR) at various positions relative to the wireless device, SAR measurements may be performed over a two-dimensional (2D) surface covering the device for a given operating scenario. Subsequently, three-dimensional (3D) volume SAR scans may be performed at specific locations identified on the surface scan that correspond to high SAR. In an alternative scheme, electromagnetic simulations may be performed by attempting to model the detailed physical characteristics of the wireless device. However, it is often difficult to obtain an accurate physical model for the wireless device in such cases. Furthermore, implementing the aforementioned schemes may consume a great deal of time, and may thus be impractical for state-of-the-art wireless devices that operate over a wide range of bands, number of transmitters, channels, etc.
It would be desirable to provide techniques for efficiently assessing the SAR of wireless devices to reduce the time and cost of design and certification.